A multitude of instances exist wherein it is desirable to implement a monitoring system for a given area. Such an area may be of any size and may include structures, facilities supporting the structures, infrastructures, grounds within a defined perimeter, outer perimeter grounds and structures, roadways, and the like. In many cases, it is desirable to monitor motion.
The typical motion sensor is a rather simple line-of-sight (LOS) sensor that may emit a signal or light beam. When motion in the monitored area reaches a predetermined threshold, the sensor provides an output to a monitor that may, in turn, set off an alarm or summon assistance. Other motion sensors operate on pressure. Some use a perturbation of air pressure as the sensed characteristic, while others use contact pressure as in floor sensors. These typical sensors suffer from several drawbacks. Line-of-sight (LOS) sensors are limited by objects obstructing the line-of-sight (LOS). Furthermore, these sensors are, by necessity, visible within the monitored area and can be defeated. Air pressure sensors are limited by obstructions and may not detect very slight or slow movements. Implanted pressure sensors are limited by a small sensitivity area on which contact must be made and cannot detect general movement in the monitored area. All such sensors suffer from the inability to detect other characteristics of a moving object such as distance to the motion and velocity of the motion.